Machine to machine (M2M) technology is a combination of wireless communications technology and information technology. It allows a machine to directly communicate with another machine without human intervention.
M2M communication is also referred to as machine type communication (MTC). An M2M communication system is significantly different from a traditional human to human (H2H) communication system. Due to large number of devices involved, low mobility, low communication traffic, etc., the M2M communication system has many features of a machine-type communication system. M2M communication systems are referred to as MTC communication systems in the current 3rd Generation Partnership Project (3GPP) standards. In the case of small data transmission, short message services (SMS) or Internet Protocol (IP) packets are started to be used in communications between machines.
When SMS small data or IP packet small data is encapsulated in a tracking area update (TAU) request or a new initial layer-3 message, how to provide confidentiality protection to a part of small data in the initial layer-3 message and to parameters that require protection becomes a problem.